The present invention relates in general to reinforced vertical concrete structures and, more specifically, to an improved method and clamp for splicing an extension rebar onto the top of a dowel rebar to form a joint in the reinforcement of a vertical column, wall, or like reinforced concrete body.
Clamps for splicing reinforcing bars within a vertical concrete structure, and methods for doing the same, are well known, particularly as shown in Reiland U.S. Pat. Nos. 3,245,189, 3,245,190 and 3,340,667. The clamps shown therein have performed most satisfactorily in use, both in terms of strength and durability. The present invention is directed to a further improved clamp and a new method of installing the same which is designed to minimize and simplify the effort and manpower required to form rebar splices in a vertical concrete structure, such as a column or wall.
Heretofore, rebar clamps have customarily been installed by first slipping a longitudinally split sleeve over the top of a dowel bar already in place, then sliding the sleeve downwardly to expose the top surface of the dowel rebar above the sleeve. An extension rebar is then lowered into alignment with and seated on the upper end of the dowel rebar. The sleeve is then manually raised to a position embracing the adjacent ends of both bars and a wedge hand-tightened over the sleeve flanges to maintain the sleeve in position on the rebars. The correct position is found by observation through an inspection hole in the sleeve, i.e., centering the inspection hole at the engagement of the bar ends. Finally, the wedge is driven home with a sledge hammer and the splice checked for tightness before releasing the upper bar from its temporary support.
Although such method and splices have been quite successful, commercially, they present one particular problem incidental to their use. It is difficult to prevent the clamp sleeve from slipping down on the dowel bar while hammering the wedge into place. Initially, the sleeves were held manually during the entire splicing operation. Later, a clamping bolt or set screw was added to the sleeve to hold the sleeve in place. But clamping bolts or set screws add materially to the sleeve cost and require a time-consuming manual operation for application.